Altering the Conjugation Pathway for Improved Performance of Benzobisoxazole-Based Polymer Guest Emitters in Polymer Light-Emitting Diodes

TitleAltering the Conjugation Pathway for Improved Performance of Benzobisoxazole-Based Polymer Guest Emitters in Polymer Light-Emitting Diodes
Publication TypeJournal Article
Year of Publication2012
AuthorsIntemann JJ, Hellerich ES, Tlach BC, Ewan MD, Barnes CA, Bhuwalka A, Cai M, Shinar J, Shinar R, Jeffries-El M
Journal TitleMacromolecules
Volume45
Pages6888-6897
Date Published09
Type of ArticleArticle
ISBN Number0024-9297
Accession NumberWOS:000309014000015
KeywordsEFFICIENT SYNTHESIS, electroluminescent devices, electron-transport, ENERGY-TRANSFER, highly efficient, main chain, optical-properties, para-aromatic polymers, rigid-rod polymers, thermal-properties
Abstract

Benzobisoxazoles (BBOs) are known to increase the electron affinities and improve the electron transporting properties of materials containing them. However, BBO copolymers generally do not perform well as emissive guests in guest-host PLEDs due to inefficient Forster resonance energy transfer (FRET) between host and guest. The incomplete FRET results in a large amount of host emission and limits the potential efficiencies of the devices. In all previously reported BBO copolymers, the conjugation pathway was through the oxazole rings. Herein we report six new BBO copolymers with backbone connectivity directly on the central benzene ring, resulting in a conjugation pathway for the polymers that is perpendicular to the previously reported pathway. Guest-host PLEDs made using these polymers show that the new conjugation pathway improves FRET between the poly(N-vinylcarbazole) host and the BBO-containing polymer guest. Because of highly efficient FRET, no host emission is observed even at lower guest concentrations. The improved energy transfer results in devices with luminous efficiencies up to 3.1 Cd/A, a 3-fold improvement over previously reported BBO-based PLEDs. These results indicate that the conjugation pathway plays a critical role in designing emissive materials for guest-host PLEDs.

URL<Go to ISI>://WOS:000309014000015
DOI10.1021/ma300821m
Alternate JournalMacromolecules